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+;;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10 -*-
+;;;; *************************************************************************
+;;;; FILE IDENTIFICATION
+;;;;
+;;;; Name:          transactions.cl
+;;;; Purpose:       Transaction support
+;;;; Programmers:   Marc Battyani
+;;;; Date Started:  Apr 2002
+;;;;
+;;;; $Id: transactions.cl,v 1.7 2002/09/17 17:16:43 kevin Exp $
+;;;;
+;;;; This file, part of CLSQL, is Copyright (c) 2002 by Kevin M. Rosenberg
+;;;;
+;;;; CLSQL users are granted the rights to distribute and use this software
+;;;; as governed by the terms of the Lisp Lesser GNU Public License
+;;;; (http://opensource.franz.com/preamble.html), also known as the LLGPL.
+;;;; *************************************************************************
+
+(declaim (optimize (debug 3) (speed 3) (safety 1) (compilation-speed 0)))
+(in-package :clsql-sys)
+
+;; I removed the USQL transaction stuff to put a smaller, lighter one (MB)
+
+(defclass transaction ()
+  ((commit-hooks :initform () :accessor commit-hooks)
+   (rollback-hooks :initform () :accessor rollback-hooks)
+   (status :initform nil :accessor status))) ;can be nil :rolled-back or :commited
+
+(defmethod database-start-transaction ((database closed-database))
+  (error 'clsql-closed-database-error database))
+
+(defmethod database-start-transaction (database)
+  (unless (transaction database)
+    (setf (transaction database) (make-instance 'transaction)))
+  (when (= (incf (transaction-level database)) 1)
+    (let ((transaction (transaction database)))
+      (setf (commit-hooks transaction) nil
+	    (rollback-hooks transaction) nil
+	    (status transaction) nil)
+      (execute-command "BEGIN" :database database))))
+
+(defmethod database-end-transaction ((database closed-database))
+  (error 'clsql-closed-database-error database))
+
+(defmethod database-end-transaction (database)
+  (if (> (transaction-level database) 0)
+    (when (zerop (decf (transaction-level database)))
+      (let ((transaction (transaction database)))
+	(if (eq (status transaction) :commited)
+	  (progn
+	    (execute-command "COMMIT" :database database)
+	    (map nil #'funcall (commit-hooks transaction)))
+	  (unwind-protect ;status is not :commited
+	       (execute-command "ROLLBACK" :database database)
+	    (map nil #'funcall (rollback-hooks transaction))))))
+    (warn "Continue without commit."
+	  'clsql-simple-error
+	  :format-control "Cannot commit transaction against ~A because there is no transaction in progress."
+	  :format-arguments (list database))))
+
+(defun rollback-transaction (database)
+  (when (and (transaction database)(not (status (transaction database))))
+    (setf (status (transaction database)) :rolled-back)))
+
+(defun commit-transaction (database)
+  (when (and (transaction database)(not (status (transaction database))))
+    (setf (status (transaction database)) :commited)))
+
+(defun add-transaction-commit-hook (database commit-hook)
+  (when (transaction database)
+    (push commit-hook (commit-hooks (transaction database)))))
+
+(defun add-transaction-rollback-hook (database rollback-hook)
+  (when (transaction database)
+    (push rollback-hook (rollback-hooks (transaction database)))))
+
+(defmacro with-transaction ((&key (database '*default-database*)) &rest body)
+  (let ((db (gensym "db-")))
+    `(let ((,db ,database))
+      (unwind-protect
+	   (progn
+	     (database-start-transaction ,db)
+	     ,@body
+	     (commit-transaction ,db))
+	(database-end-transaction ,db)))))